Description

If the database was set to autocommit mode, this function will restore
autocommit mode after it has rolled back the transaction.

Some databases, including MySQL, automatically issue an implicit
COMMIT when a database definition language (DDL) statement such as
DROP TABLE or CREATE TABLE is issued within a transaction. The implicit
COMMIT will prevent you from rolling back any other changes within the
transaction boundary.

Return Values

Returns TRUE on success or FALSE on failure.

Examples

Example #1 Roll back a transaction

The following example begins a transaction and issues two statements
that modify the database before rolling back the changes. On MySQL,
however, the DROP TABLE statement automatically commits the
transaction so that none of the changes in the transaction are rolled
back.

Here is a way of testing that your transaction has started when using MySQL's InnoDB tables. It will fail if you are using MySQL's MyISAM tables, which do not support transactions but will also not return an error when using them.

<?// Begin the transaction$dbh->beginTransaction();

// To verify that a transaction has started, try to create an (illegal for InnoDB) nested transaction.// If it works, the first transaction did not start correctly or is unsupported (such as on MyISAM tables)try {$dbh->beginTransaction(); die('Cancelling, Transaction was not properly started');} catch (PDOException $e) { print "Transaction is running (because trying another one failed)\n";}?>

Should anyone reading this be slightly panicked because they just discovered that their MySQL tables are MyIsam and not InnoDb, don't worry... You can very easily change the storage engine using the following query: